• Journal of Microbiology and Biotechnology
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• v.23 no.7
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• pp.942-952
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• 2013

Monoliths are functional porous materials with a three-dimensional continuous interconnected pore structure in a single piece. A monolith with uniform shape based on poly(${\gamma}$-glutamic acid) (PGA) has been prepared via a thermally induced phase separation technique using a mixture of dimethyl sulfoxide, water, and ethanol as solvent. The morphology of the obtained monolith was observed by scanning electron microscopy and the surface area of the monolith was evaluated by the Brunauer Emmett Teller method. The effects of fabrication parameters such as the concentration and molecular mass of PGA and the solvent composition have been systematically investigated. The PGA monolith was cross-linked with hexamethylene diisocyanate to produce the water-insoluble monolith. The addition of sodium chloride to the phase separation solvent affected the properties of the cross-linked monolith. The swelling ratio of the cross-linked monolith toward aqueous solutions depended on the buffer pH as well as the monolith fabrication condition. Copper(II) ion was efficiently adsorbed on the cross-linked PGA monolith, and the obtained copper-immobilized monolith showed strong antibacterial activity for Escherichia coli. By combination of the characteristic properties of PGA (e.g., high biocompatibility and biodegradability) and the unique features of monoliths (e.g., through-pore structure, large surface area, and high porosity with small pore size), the PGA monolith possesses large potentials for various industrial applications in the biomedical, environmental, analytical, and separation fields.

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.10 no.1
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• pp.65-72
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• 2010

For developing navigation system of total hip arthroplasty (THA) and evaluating hip joint kinematics, 3-D pose position of the femur and acetabulum in the pelvic coordinate system has been quantified. The pelvic coordinate system is determined by manually indicating pelvic landmarks in multidetector-row computed tomography (MDCT) images. It includes intra- and inter-observer variability, and may result in a variability of THA operation or diagnosis. To reduce the variability of pelvic coordinate system determination, this paper proposes an automated method in MDCT images. The proposed method determines pelvic coordinate system automatically by detecting pelvic landmarks on anterior pelvic plane (APP) from MDCT images. The method calibrates pelvic pose by using silhouette images to suppress the affect of pelvic pose change. As a result of comparing with manual determination, the proposed method determined the coordinate system with a mean displacement of $2.6\;{\pm}\;1.6$ mm and a mean angle error of $0.78\;{\pm}\;0.34$ deg on 5 THA subjects. For changes of pelvic pose position within 10 deg, standard deviation of displacement was 3.7 mm, and of pose was 1.28 deg. We confirmed the proposed method was robust for pelvic pose changes.

• Diabetes and Metabolism Journal
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• v.42 no.6
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• pp.488-495
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• 2018

Background: Skeletal muscle plays a major role in glucose metabolism. We investigated the association between thigh muscle mass, insulin resistance, and incident type 2 diabetes mellitus (T2DM) risk. In addition, we examined the role of body mass index (BMI) as a potential effect modifier in this association. Methods: This prospective study included 399 Japanese Americans without diabetes (mean age 51.6 years) who at baseline had an estimation of thigh muscle mass by computed tomography and at baseline and after 10 years of follow-up a 75-g oral glucose tolerance test and determination of homeostasis model assessment of insulin resistance (HOMA-IR). We fit regression models to examine the association between thigh muscle area and incidence of T2DM and change in HOMA-IR, both measured over 10 years. Results: Thigh muscle area was inversely associated with future HOMA-IR after adjustment for age, sex, BMI, HOMA-IR, fasting plasma glucose, total abdominal fat area, and thigh subcutaneous fat area at baseline (P=0.033). The 10-year cumulative incidence of T2DM was 22.1%. A statistically significant interaction between thigh muscle area and BMI was observed, i.e., greater thigh muscle area was associated with lower risk of incident T2DM for subjects at lower levels of BMI, but this association diminished at higher BMI levels. Conclusion: Thigh muscle mass area was inversely associated with future insulin resistance. Greater thigh muscle area predicts a lower risk of incident T2DM for leaner Japanese Americans.

• Asian Spine Journal
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• v.12 no.6
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• pp.1078-1084
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• 2018

Study Design: Prospective observational study. Purpose: This prospective analysis aimed to evaluate the efficacy and bone-bonding rate of hybrid hydroxyapatite (HA) spacers in expansive laminoplasty. Overview of Literature: Various types of spacers or plates have been developed for expansive laminoplasty. Methods: Expansive open-door laminoplasty was performed in 146 patients with cervical myelopathy; 450 hybrid HA spacers and 41 autogenous bone spacers harvested from the spinous processes were grafted into the opened side of each lamina. The patients were followed up using computed tomography (CT), and their bone-bonding rates for hybrid HA and autogenous spacers, bone-fusion rates of the hinges of the laminae, and complications associated with the implants were then examined. Results: Clinical symptoms significantly improved in all patients, and no major complications related to the procedure were noted. The hybrid HA spacers exhibited sufficient bone bonding on postoperative CT. The hinges completely fused in over 95% patients within 1 year of the procedure. Only 4 spacers (0.9%) developed lamina sinking, and most expanded laminae maintained their positions without sinking or floating throughout the follow-up period. Conclusions: Hybrid HA spacers contributed to high bone-fusion rates of the spacers and hinges of the laminae, and no complications were associated with their use. Cervical laminoplasty with these spacers is safe and simple, and it yields sufficient fixation strength while ensuring sufficient bone bonding during the immediate postoperative period.

• Neurospine
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• v.15 no.4
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• pp.362-367
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• 2018

Objective: To assess the efficacy of cervical open-door laminoplasty by hydroxyapatite implant insertion between the lamina and the lateral mass without suturing. Methods: All patients who underwent cervical open-door laminoplasty with C2/C7 undermining and insertion of hydroxyapatite implants from C3 to C6 were retrospectively evaluated for surgical time and neurological outcomes according to the Japanese Orthopaedic Association (JOA) score. To assess the alignment of the cervical spine and postoperative cervical pain, the C2-7 angle and a visual analogue scale score were used, respectively. Results: The population consisted of 102 women and 222 men ranging in age from 32 to 90 years. The average surgical time was 86 minutes. Fourteen of 1,296 hydroxyapatite implants were kept in place with sutures due to a weak restoration force of the hinge during surgery. No hydroxyapatite implant dislocation was detected on cervical computed tomography at 1 year after surgery. The average JOA score was $10.2{\pm}2.5$ before surgery and $14.6{\pm}2.8$ at 1 year after surgery. The average recovery rate was 61.8%. The average C2-7 angle at the neutral position was $7.1^{\circ}{\pm}6.2^{\circ}$ before surgery and $6.5^{\circ}{\pm}6.3^{\circ}$ at 1 year after surgery. Conclusion: This method enabled us to achieve minimal exposure of the lateral mass, prevention of lateral mass injury and dural injury, and a shorter surgical time while maintaining acceptable surgical outcomes. The idea that firm suture fixation is needed to prevent spacer deviation during cervical open-door laminoplasty may need to be revisited.

• Journal of the Korean Wood Science and Technology
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• v.49 no.1
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• pp.57-66
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• 2021

In recent years, the use of cross laminated timber (CLT) has been evolving. In addition, CLT manufactured with various species such as Japanese cedar has been developed to utilize the local resources in each country. However most factories in Japan produce CLT by bonding the laminae in width direction for orthogonal layers, where grain of element is perpendicular to the grain of outer layer, and this process is considered to be one of the factors that reduce productivity. A new wood based material (hereinafter referred to as Ply-lam) using wooden panel such as plywood for the orthogonal layer was developed in order to improve productivity in CLT manufacturing and improve quality. Japanese cypress lamina was used for the parallel layer, where grain of element is parallel to the grain of outer layer, of CLT and Korean larch plywood was used for the orthogonal layer, in order to effectively use Korean larch and expand the utilization of Japanese cypress. The cross-sectional construction of the Ply-lam was 5-layers 5-plies, and the dimensions were 1000 mm (width) × 150 mm (depth) × 4000 mm (length). As a performance evaluation of the manufactured Ply-lam, strength tests such as out-of-plane bending, in-plane bending, out-of-plane shearing and in-plane shearing tests were carried out. As the result of this study, Ply-lam composed of Japanese cypress lamina panels and Korean larch plywood showed very higher out-of-plane bending strength compared to the standard strength of CLT. And the result obtained in other tests seems to show a sufficiently high value.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1994.04a
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• pp.82-87
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• 1994

자동차 엔진의 주기적인 연소과정 동아네 생성된 힘에 의해 엔진의 크랭크 샤프트에 회전 불균일성이 나타난다. 이것은 엔진 플라이휘일 부분에 비틀림 변동토크를 발생시키고, 이 토크는 클러치를 통하여 변속기의 인풋기어(input gear)에 전달되어 변속기에 비틀림 진동을 일으키는 주요 원인이 된다. 공회전시 변속기에서 기어의 충돌은 주로 이 비틀림 변동토크에 의해 발생하며, 이 충돌은 차내 소음의 원인이 된다. 또한 엔진의 경량화 및 고출력화에 따른 회전수 변동의 증가는 비틀림 변동토크를 증가시켜 변속기에 커다란 진동을 초래한다. 시뮬레이션을 사용한 클러치 비틀림 기구의 적절한 특성치를 구하는 것은 클러치 설계에 효율적이고, 이미 여러 연구 결과들이 보고되었다. H.Arai은 2자유도 비선형 모델을 사용하여 클러치 접속시 발생하는 외란과 계의 안정성을 고려하여 치타음 저감을 위한 시뮬레이션을 수행하였고, S.Ohnuma은 비선형 2단 비틀림 특성을 가진 클러치 디스크의 설계에 대해서, 그리고, T.Fujimoto와 R.J.Comparin는 치타음의 발생구조와 특성을 고찰하고 비선형 비틀림 공진 저감에 의한 치타음 저감 기법에 대하여 연구하였다. 그리고, Wu Hui-Le는 자동차 동력전달계의 비틀림 진동 현상을 실험과 이론적인 계산을 통해 연구하였고, G.J.Fudala는 다자유도 모델을 이용하여 클러치의 비틀림 특성에 따라 주파수분석을 수행하여 치타음 저감 방법을 연구하였다. 또한, T.Sakai는 5자유도 모델을 이용하여 엔진 공회전시 발생하는 치타음에 대해 이론과 실험을 통해 해석하고, 엔진 회전수 변동, 클러치 특성, 변속기의 드래그(drag) 토크의 영향과 치타음 저감을 위한 개선된 클러치 특성을 제시하였다. 클러치는 동력을 전달 또는 차단하는 기능 뿐만 아니라 엔진이나 변속기에서 발생하는 소음이나 진동을 저감시키는 기능을 가지고 있다. 따라서 엔진 공회전시에 발생하는 치타음(rattle noise)이나 비틀림 진동을 저감시키는 방법으로는 여러가지가 있으나 클러치 디스크(clutch disc)의 비틀림 기구의 설계 인자들을 적절히 조절함으로써 변속기의 인풋기어에 전달되는 비틀림 진동을 저감시키는 방법이 일반적으로 수행되어지고 있다. 본 연구는 4 실린더 4 싸이클 1.5L 엔진을 장착한 경승용차의 실차실험을 통해 공회전시 엔진 플라이휘일과 인풋기어에서의 회전수 변동을 측정하고, 이 실험 데이타를 기초로 하여 엔진 토크 및 변속기에서의 드래그 토크를 계산하여 엔진-변속기 인풋기어의 반한정계 2자유도 진동모델과 비틀림 특성을 가진 클러치 디스크의 프리댐퍼 영역에 대해 시뮬레이션을 수행하여 클러치 비틀림 기구의 설계인자인 비틀림 강성, 히스테리시스 토크에 따른 비틀림 진동 저감 효과를 연구하고자 한다.

• Journal of the Microelectronics and Packaging Society
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• v.8 no.3
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• pp.37-42
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• 2001

The concerns of the toxicity and health hazard of lead in solders have demanded the research to find suitable lead-free solder alloys. It was discussed that effect of the intermetallic formation and structure on the reliability of solder joints. In this study, lead-free solder alloys with compositions of Sn/3.5Ag/0.75Cu, Sn/2.0Ag/0.5Cu/2.0Bi were applied to the 48 $\mu$BGA packages. Also, the lead-free solder alloys compared with eutectic Sn/37Pb solder using shear test under various aging temperature. Common $\mu$BGA with solder components was aged at $130^{\circ}C$, $150^{\circ}C$ and $170^{\circ}C$. And the each temperature applied to 300, 600 and 900 hours. The thickness of the intermetallics was measured for each condition and the activation energy for their growth was computed. The fracture surfaces were analyzed using SEM (Scanning Electron Microscope) with EDS (Energy Dispersive Spectroscopy). These results for reliability of lead-free interconnections are discussed.

• Journal of the Society of Naval Architects of Korea
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• v.36 no.4
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• pp.137-146
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• 1999

Inspection becomes to be important in the safety of structure and economical viewpoint, because structural damage accompanies lots of economical cost and social problems. Especially ship structure is composed of a lot of members and it is impossible to inspect all members continuously. The purpose of this paper is to get optimal inspection plan containing inspection time and method. Crack is one of major modes on the structural failure and can lead to collapse of structure. In this paper, the deteriorating process, which contains inspection to detect the crack before the propagation to large crack, is idealized as Markov chain model. Genetic algorithm is also used to accomplish the optimization of inspection plan. Especially, the probabilistic characteristics of cracks are changed, because ship is operating in corrosive environments and the scantling of structural members is reduced due to corrosion. Non-stationary Markov chain model is used to represent the process of corrosion in structural members. In this paper, the characteristics of indivisual inspection plan are compared by numerical examples for the change of corrosion rate, the cost due to scheduled system down and target failure probability. From the numerical example, it can be seen that the improvement of fatigue life for the members with short fatigue life is the most effective way in order to reduce total maintenance cost.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.5 no.1
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• pp.1-10
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• 1972

Studies on the circulation and water masses in the continental shelf break region of the East China Sea are Summerized as follows : 1. The main stream of the Kuroshio flowing north-east near $29^{\circ}N\;Lat\;127^{\circ}E$ tong of the East China Sea in summer is narrow in width. Moving toward east, it becomes twice as wide in Tokora Strait, Japan. 2. In the main stream area of the Kuroshio, the surface Waters in the Upper layer (0-250m) are influenced by the coastal waters of China, and the counter current submerges under the surface water. Therefore, the mixing waters are found in its intermediate layer. 3. Water mass between Amami Island and the continental shelf of the East China Sea consists of main stream water, counter current water, gyration water and mixed water with coastal waters. 4. The maximum velocity of current in this waters was 139cm/sec. The volume transport was estimated approximately as $24.2\;\times\;10^6m^3/sec$. It was less than $33\;\times\;10^6m^3/sec$ in the region between Okinawa and continental shelf of the East China Sea. 5. Surface waters east of $29^{\circ}N\;Lat\;128^{\circ}E$ Long flows toward Amami Island, Okinawa Island, and Hachi Ju San Island, while those west of the region flow toward the Korea-strait, Cheju Island, coastal waters of Kyusyu, and the Pacific Ocean through Tokora Strait. The velocity of the current was estimated approximately as $0.3\~0.5$ miles per hour. 6. The bottom waters in the continental shelf break region flow toward the Korea Strait, Cheju Island and the coastal water of Kyusyu, while that of the continental shelf flows toward the Yellow Sea, 7, The characteristics of the Kuroshio water is changed remarkably by the mixing with the coastal water of China.